Electrosurgical apparatus with real-time RF tissue energy control

ABSTRACT

A radio-frequency (RF) amplifier having a direct response to an arbitrary signal source to output one or more electrosurgical waveforms within an energy activation request, is disclosed. The RF amplifier includes a phase compensator coupled to an RF arbitrary source, the phase compensator configured to generate a reference signal as a function of an arbitrary RF signal from the RF arbitrary source and a phase control signal; at least one error correction amplifier coupled to the phase compensator, the at least one error correction amplifier configured to output a control signal at least as a function of the reference signal; and at least one power component coupled to the at least one error correction amplifier and to a high voltage power source configured to supply high voltage direct current thereto, the at least one power component configured to operate in response to the control signal to generate at least one component of the at least one electrosurgical waveform.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patent application Ser. No. 14/692,195, filed Apr. 21, 2015, which is a continuation of U.S. patent application Ser. No. 13/195,607, filed on Aug. 1, 2011, now U.S. Pat. No. 9,028,479. The entire contents of all of the foregoing applications are incorporated by reference herein.

BACKGROUND Technical Field

The present disclosure relates to electrosurgical apparatuses, systems and methods. More particularly, the present disclosure is directed to an electrosurgical generator adapted for real-time adjustment of its output.

Background of Related Art

Energy-based tissue treatment is well known in the art. Various types of energy (e.g., electrical, ultrasonic, microwave, cryogenic, heat, laser, etc.) are applied to tissue to achieve a desired result. Electrosurgery involves application of high radio frequency electrical current, microwave energy or resistive heating to a surgical site to cut, ablate, coagulate or seal tissue.

In bipolar electrosurgery, one of the electrodes of the hand-held instrument functions as the active electrode and the other as the return electrode. The return electrode is placed in close proximity to the active electrode such that an electrical circuit is formed between the two electrodes (e.g., electrosurgical forceps). In this manner, the applied electrical current is limited to the body tissue positioned between the electrodes.

Bipolar electrosurgical techniques and instruments can be used to coagulate blood vessels or tissue, e.g., soft tissue structures, such as lung, brain and intestine. A surgeon can either cauterize, coagulate/desiccate and/or simply reduce or slow bleeding, by controlling the intensity, frequency and duration of the electrosurgical energy applied between the electrodes and through the tissue. In order to achieve one of these desired surgical effects without causing unwanted charring of tissue at the surgical site or causing collateral damage to adjacent tissue, e.g., thermal spread, it is necessary to control the output from the electrosurgical generator, e.g., power, waveform, voltage, current, pulse rate, etc.

In monopolar electrosurgery, the active electrode is typically a part of the surgical instrument held by the surgeon that is applied to the tissue to be treated. A patient return electrode is placed remotely from the active electrode to carry the current back to the generator and safely disperse current applied by the active electrode. The return electrodes usually have a large patient contact surface area to minimize heating at that site. Heating is caused by high current densities which directly depend on the surface area. A larger surface contact area results in lower localized heat intensity. Return electrodes are typically sized based on assumptions of the maximum current utilized during a particular surgical procedure and the duty cycle (i.e., the percentage of time the generator is on).

Conventional electrosurgical generators operate in one operational mode (e.g., cutting, coagulation, spray, etc.) which is set prior to commencement of the procedure during a given activation period. If during treatment a need arises to switch form one mode to another, such as during a cutting procedure when a vessel is cut and begins to bleed, the first mode (e.g., cutting) is terminated manually and the second mode (e.g., coagulation) is switched on. There is a need for an electrosurgical generator which can switch between a plurality of modes automatically in response to sensed tissue and/or energy feedback signals.

SUMMARY

A radio-frequency (RF) amplifier for outputting at least one electrosurgical waveform is disclosed. The RF amplifier includes a phase compensator coupled to an RF arbitrary source, the phase compensator configured to generate a reference signal as a function of an arbitrary RF signal from the RF arbitrary source and a phase control signal; at least one error correction amplifier coupled to the phase compensator, the at least one error correction amplifier configured to output a control signal at least as a function of the reference signal; and at least one power component coupled to the at least one error correction amplifier and to a high voltage power source configured to supply high voltage direct current thereto, the at least one power component configured to operate in response to the control signal to generate at least one component of the at least one electrosurgical waveform.

In another embodiment, an RF amplifier configured to output at least one electrosurgical waveform in response to an arbitrary RF signal is disclosed. The RF amplifier includes a phase compensator coupled to an RF arbitrary source, the phase compensator configured to generate a reference signal as a function of an arbitrary RF signal from the RF arbitrary source and a phase control signal; at least one error correction amplifier coupled to the phase compensator, the at least one error correction amplifier configured to output a control signal at least as a function of the reference signal; at least one power component coupled to the at least one error correction amplifier, the at least one power component configured to operate in response to the control signal to generate at least one component of the at least one electrosurgical waveform; at least one current sensor configured to measure current of the at least one electrosurgical waveform and to operate with the at least one power component to output a current control signal as a function of the measured current; a patient isolation transformer coupled to the RF amplifier, the patient isolation transformer including a primary winding coupled to the at least one power component, wherein the patient isolation is the only isolation coupling component for delivering the at least one electrosurgical waveform to a patient and is configured to operate in a phase-correlated manner with the at least one electrosurgical waveform of the RF amplifier; and a high voltage power source configured to supply high voltage direct current to the RF amplifier.

In embodiments, an electrosurgical generator is disclosed. The generator includes a high voltage power source configured to supply high voltage direct current; an RF arbitrary source configured to generate an arbitrary RF signal; and a radio-frequency (RF) amplifier configured to output at least one electrosurgical waveform. The RF amplifier includes: a phase compensator coupled to the RF arbitrary source, the phase compensator configured to generate a reference signal as a function of the arbitrary RF signal from the RF arbitrary source and a phase control signal; at least one error correction amplifier coupled to the phase compensator, the at least one error correction amplifier configured to output a control signal at least as a function of the reference signal; and at least one power component coupled to the at least one error correction amplifier and to the high voltage power source, the at least one power component configured to operate in response to the control signal to generate at least one component of the at least one electrosurgical waveform. The generator also includes a controller configured to adjust at least one of the arbitrary RF signal and the phase control signal in response to at least one selected electrosurgical operational mode.

According to another embodiment of the present disclosure, an electrosurgical generator is disclosed. The generator includes a high voltage power source configured to supply high voltage direct current; an RF arbitrary source configured to generate an arbitrary RF signal; and one or more radio-frequency (RF) amplifiers configured to output at least one electrosurgical waveform. The radio-frequency (RF) amplifiers include: a phase compensator coupled to the RF arbitrary source, the phase compensator configured to generate a reference signal as a function of the arbitrary RF signal from the RF arbitrary source and a phase control signal; a first control loop and a second control loop. The first control loop includes a first error correction amplifier coupled to the phase compensator, the first error correction amplifier configured to output a first control signal at least as a function of the reference signal and a first power component coupled to the first error correction amplifier and to the high voltage power source, the first power component configured to operate in response to the first control signal to generate a first component of the at least one electrosurgical waveform. The second control loop includes a second error correction amplifier coupled to the phase compensator, the second error correction amplifier configured to output a second control signal at least as a function of the reference signal; and a second power component coupled to the second error correction amplifier and to the high voltage power source, the second power component configured to operate in response to the second control signal to generate a second component of the at least one electrosurgical waveform. The generator also includes a controller configured to adjust at least one of the arbitrary RF signal and the phase control signal in response to at least one selected electrosurgical operational mode.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present disclosure are described herein with reference to the drawings wherein:

FIG. 1 is a schematic block diagram of an electrosurgical system according to one embodiment of the present disclosure;

FIG. 2 is a front view of an electrosurgical generator according to an embodiment of the present disclosure;

FIG. 3 is a schematic block diagram of the electrosurgical generator of FIG. 2 according to an embodiment of the present disclosure; and

FIG. 4 is a schematic block diagram of a radio frequency amplifier of the electrosurgical generator of FIG. 3 according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

Particular embodiments of the present disclosure are described hereinbelow with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail.

The generator according to the present disclosure can perform monopolar and/or bipolar electrosurgical procedures, including vessel sealing procedures. The generator may include a plurality of outputs for interfacing with various electrosurgical instruments (e.g., a monopolar active electrode, return electrode, bipolar electrosurgical forceps, footswitch, etc.). Further, the generator includes electronic circuitry configured for generating radio frequency power specifically suited for various electrosurgical modes (e.g., ablation, coagulation, cutting, blending, division, etc.) and procedures (e.g., monopolar, bipolar, vessel sealing).

FIG. 1 is a schematic illustration of a bipolar and monopolar electrosurgical system 1 according to one embodiment of the present disclosure. The system 1 includes one or more monopolar electrosurgical instruments 2 having one or more electrodes (e.g., electrosurgical cutting probe, ablation electrode(s), etc.) for treating tissue of a patient. Electrosurgical energy is supplied to the instrument 2 by a generator 20 via a supply line 4 that is connected to an active terminal 30 of the generator 20, allowing the instrument 2 to coagulate, ablate and/or otherwise treat tissue. The energy is returned to the generator 20 through a return electrode 6 via a return line 8 at a return terminal 32 of the generator 20. The system 1 may include a plurality of return electrodes 6 that are arranged to minimize the chances of tissue damage by maximizing the overall contact area with the patient. In addition, the generator 20 and the return electrode 6 may be configured for monitoring so-called “tissue-to-patient” contact to insure that sufficient contact exists therebetween to further minimize chances of tissue damage.

The system 1 may also include a bipolar electrosurgical forceps 10 having one or more electrodes for treating tissue of a patient. The electrosurgical forceps 10 includes opposing jaw members having one or more active electrodes 14 and a return electrode 16 disposed therein. The active electrode 14 and the return electrode 16 are connected to the generator 20 through cable 18 that includes the supply and return lines 4, 8 coupled to the active and return terminals 30, 32, respectively. The electrosurgical forceps 10 is coupled to the generator 20 at a connector 60 or 62 (FIG. 2) having connections to the active and return terminals 30 and 32 (e.g., pins) via a plug (not shown) disposed at the end of the cable 18, wherein the plug includes contacts from the supply and return lines 4, 8.

With reference to FIG. 2, the generator 20 may be any suitable type (e.g., electrosurgical, microwave, etc.) and may include a plurality of connectors 50-62 to accommodate various types of electrosurgical instruments (e.g., multiple instruments 2, electrosurgical forceps 10, etc.). With reference to FIG. 2, front face 40 of the generator 20 is shown. The generator 20 includes one or more display screens 42, 44, 46 for providing the user with variety of output information (e.g., intensity settings, treatment complete indicators, etc.). Each of the screens 42, 44, 46 is associated with a corresponding connector 50-62. The generator 20 includes suitable input controls (e.g., buttons, activators, switches, touch screen, etc.) for controlling the generator 20. The display screens 42, 44, 46 are also configured as touch screens that display a corresponding menu for the electrosurgical instruments (e.g., multiple instruments 2, electrosurgical forceps 10, etc.). The user then makes inputs by simply touching corresponding menu options.

The generator 20 is configured to operate in a variety of modes. In one embodiment, the generator 20 may output the following modes, cut, blend, division with hemostasis, fulgurate and spray. Each of the modes operates based on a preprogrammed power curve that dictates how much power is output by the generator 20 at varying impedance ranges of the load (e.g., tissue). Each of the power curves includes power, voltage and current control range that are defined by the user-selected power setting and the measured minimum impedance of the load.

In the cut mode, the generator 20 may supply a continuous sine wave at a predetermined frequency (e.g., 472 kHz) having a crest factor of about 1.5 with an impedance of from about 100Ω to about 2,000Ω. The cut mode power curve may include three regions: constant current into low impedance, constant power into medium impedance and constant voltage into high impedance. In the blend mode, the generator may supply bursts of a sine wave at the predetermined frequency, with the bursts reoccurring at a first predetermined rate (e.g., about 26.21 kHz). In one embodiment, the duty cycle of the bursts may be about 50%. The crest factor of one period of the sine wave may be about 1.5. The crest factor of the burst may be about 2.7.

The division with hemostasis mode may include bursts of sine waves at a predetermined frequency (e.g., 472 kHz) reoccurring at a second predetermined rate (e.g., about 28.3 kHz). The duty cycle of the bursts may be about 25%. The crest factor of one burst may be about 4.3 across an impedance of from about 100Ω to about 2,000Ω. The fulgurate mode may include bursts of sine waves at a predetermined frequency (e.g., 472 kHz) reoccurring at a third predetermined rate (e.g., about 30.66 kHz). The duty cycle of the bursts may be about 6.5% and the crest factor of one burst cycle may be about 5.55 across an impedance range of from about 100Ω to about 2,000Ω. The spray mode may include bursts of sine wave at a predetermined frequency (e.g., 472 kHz) reoccurring at a fourth predetermined rate (e.g., about 21.7 kHz). The duty cycle of the bursts may be about 4.6% and the crest factor of one burst cycle may be about 6.6 across the impedance range of from about 100Ω to about 2,000Ω.

The screen 46 of FIG. 2 controls bipolar sealing procedures performed by the forceps 10 that may be plugged into the connectors 60 and 62. The generator 20 outputs energy through the connectors 60 and 62 suitable for sealing tissue grasped by the forceps 10. The screens 42 and 44 control monopolar output and the devices connected to the connectors 50 and 56. The connector 50 is configured to couple to the instrument 2 and the connector 52 is configured to couple to a foot switch (not shown). The foot switch provides for additional inputs (e.g., replicating inputs of the generator 20 and/or instrument 2). The screen 44 controls monopolar and bipolar output and the devices connected to the connectors 56 and 58, respectively. Connector 56 is configured to couple to the instrument 2, allowing the generator 20 to power multiple instruments 2. Connector 58 is configured to couple to a bipolar instrument (not shown). When using the generator 20 in monopolar mode (e.g., with instruments 2), the return electrode 6 is coupled to the connector 54, which is associated with the screens 42 and 44. The generator 20 is configured to output the modes discussed above through the connectors 50, 56, 58.

FIG. 3 shows a system block diagram of the generator 20 configured to output electrosurgical energy. The generator 20, a controller 24, a high voltage DC power supply 27 (“HVPS”), a radio frequency amplifier 28, including an RF amplifier 28 a and an RF amplifier 28 b, includes a radio frequency (RF) arbitrary source 34, a sense processor 36, and a patient isolation transformer 38 including a primary winding 38 a and a secondary winding 38 b.

The HVPS 27 of FIG. 3 is configured to output high DC voltage from about 15 V DC to about 200 V DC and is connected to an AC source (e.g., electrical wall outlet) and provides high voltage DC power to the RF amplifier 28, which then converts high voltage DC power into radio frequency energy and delivers the energy to the terminals 30 and 32, which are, in turn, coupled to the connectors 50-62 for supplying energy to the instrument 2 and the return pad 6 or the forceps 10. The HVPS 27 is coupled to the RF amplifiers 28 a and 28 b and provides DC energy thereto in a transparent manner to the operation of the RF amplifiers 28 a and 28 b. In particular, the controller 24 provides an HVPS control signal to drive the positive and negative potentials of the HVPS 27 for each of the RF amplifiers 28 a and 28 b with sufficient power to allow for uninhibited operation of the RF amplifiers 28 a and 28 b. In other words, the controller 24 may control the RF amplifiers 28 a and 28 b via the RF arbitrary source 34 or directly without adjusting the HVPS 27.

The RF arbitrary source 34 may be any RF signal generator such as a voltage controlled oscillator, a direct digital synthesizer, or any suitable frequency generator configured to generate arbitrary waveforms from a fixed frequency reference clock. As herein, the term “arbitrary” denotes an RF signal that may be any arbitrarily defined waveform, e.g., any frequency, amplitude, duty cycle, etc. The RF arbitrary source 34 supplies an RF signal to the RF amplifiers 28 a and 28 b. In embodiments, the RF signal may be a bipolar two-quadrant sinusoidal arbitrary RF signal. The RF amplifiers 28 a and 28 b process the RF arbitrary source signal and generate a differential RF drive signal to the patient isolation transformer 38. RF output parameters, such as operating RF power, voltage and current amplitude, operating frequency, gain parameters, phase compensation, time dependent configuration of the RF arbitrary source 34, are processed by the RF amplifiers 28 a and 28 b to deliver prescribed RF clinical treatment energy to achieve a desired tissue effect.

The RF amplifier 28 a and RF amplifier 28 b are coupled to the primary winding 38 a of the patient isolation transformer 38. The RF amplifier 28 a is configured to output a positive half-cycle having a phase angle from about 0° to about 180° and the RF amplifier 28 b is configured to output a negative half-cycle having a phase angle from about 0° to about −180°. Thus, while the RF amplifier 28 a is providing sourcing RF current (e.g., outputs positive current), the RF amplifier 28 b is providing sinking current (e.g., outputs negative current). Conversely, while the RF amplifier 28 b is providing sourcing RF current (e.g., outputs positive current), the RF amplifier 28 a is providing sinking current (e.g., outputs negative current).

The patient isolation transformer 38 combines the differential RF drive output of the RF amplifiers 28 a and 28 b to deliver phase correlated RF energy (e.g., waveform) across to the secondary winding 38 b to the terminals 30 and 32 with high signal-to-noise immunity to common-mode generated, spurious processing noise. In other words, the differential RF drive output provides the common mode rejection and cancels spurious corruptive noise energy from altering the prescribed clinical treatment tissue effect. This allows for the phase-correlated RF energy to be adjustable, providing potential for new control modes to dynamically alter in real-time the crest factor and other parameters of the delivered RF waveshape within a given applied energy activation period.

The sense processor 36 is coupled to a voltage sensor 41 and a current sensor 43. The voltage sensor 41 includes a resistor element 45 that provides an RF current weighted measurement of the delivered RF voltage to the terminals 30 and 32. A current transformer 47 then converts the weighted value of the RF voltage to provide a voltage sense signal to the sense processor 36 for processing. The current sensor 43 similarly provides a current sense signal to the sense processor 36.

The sense processor 36 then transmits the voltage and current sense signals to the controller 24, which adjusts RF output parameters in response to algorithm controls within a given RF activation period in real-time. In particular, the controller 24 adjusts the amplitude, frequency, waveshape and time-dependent configuration of the RF arbitrary source 34 during the given RF activation period to deliver a variety of RF treatment modes. The treatment modes may include waveforms having a duty cycle from about 5% to about 100% and may be either continuous waves or variant duty cycle RF bursts, or alternate in single or multiple combinations between modes to create a specific RF mode sequence. In embodiments, the controller 24 is configured to control the RF arbitrary source 34, the RF amplifier 28 a and 28 b, and/or the HVPS 27 in response to a selected electrosurgical operational mode, which may be selected from a plurality of electrosurgical operational modes. Each electrosurgical operational mode may be associated with at least one radio frequency input signal corresponding to a desired output electrosurgical waveform.

The controller 24 may include a microprocessor operably connected to a memory, which may be volatile type memory (e.g., RAM) and/or non-volatile type memory (e.g., flash media, disk media, etc.). The controller 24 may also include a plurality of output ports that are operably connected to the HVPS 27 and the RF amplifiers 28 a and 28 b allowing the controller 24 to control the output of the generator 20. More specifically, the controller 24 adjusts the operation of the HVPS 27 and the RF amplifiers 28 a and 28 b in response to a control algorithm that is implemented to track output of the RF amplifiers 28 a and 28 b to provide for sufficient power from the HVPS 27. In particular, as discussed in more detail below with respect to FIG. 4, the controller 24 supplies gain and phase control signals to each of the RF amplifiers 28 a and 29 b. In embodiments, a control algorithm may also inhibit or limit the output of RF amplifiers 28 a and 28 b to fit within the power supply limitations.

FIG. 4 illustrates the components of the RF amplifier 28 a. The circuit design of RF amplifier 28 b is substantially similar to the RF amplifier 28 a, with the exception for the phase relationship, as discussed above, accordingly, only the RF amplifier 28 a is discussed. The RF amplifier 28 a is a non-resonant multi-frequency transconductance amplifier configured to generate an RF current output for an applied RF voltage input. The RF voltage input signal may have an arbitrary waveshape as provided by the RF arbitrary source 34 as discussed above.

The RF amplifier 28 a is configured to operate with two RF control loops 100 a and 100 b to control each of the components of an electrosurgical waveform, e.g., each half of an applied two-quadrant sinusoidal or non-sinusoidal arbitrary RF signal input, having symmetric or non-symmetric waveshape and variable timing, to address user configurable operating modes for achieving the desired clinical effect. RF control loops 100 a and 100 b are closed loop controlled RF channels where each positive or negative half of the applied sinusoidal input is processed independently. Control loop 100 a processes the negative half-cycle of the applied sinusoidal input, driving a power component 102 a to create a positive half cycle source current at the primary side 38 a of the patient isolation transformer 38. Control loop 100 b processes the positive half-cycle of the applied sinusoidal input, driving a power component 102 b to create a negative half cycle source current at the primary side 38 a of the patient isolation transformer 38. The power components 102 a and 102 b are shown as p-type and n-type metal-oxide semiconductor field-effect transistors, respectively. In embodiments, the power components 102 a and 102 b may be any p-type or n-type transistor, MOSFET, insulated gate bipolar transistor, (IGBT), relay, and the like. The patient isolation transformer 38 combines the developed RF current from the RF amplifiers 28 a and 28 b at the secondary winding 38 b to generate the arbitrary sinusoidal RF output that is the supplied to the terminals 30 and 32 for delivery to the tissue site.

Only the control loop 100 a is discussed in detail, since the control loop 100 b is substantially identical with like components being labeled with same identifiers having a letter “b.” The arbitrary RF signal from the RF arbitrary source 34 is applied at an input 104 of a phase compensator 108. In addition, a phase control signal from the controller 24 is applied at an input 106 at the phase compensator 108. The phase compensator 108 establishes the output phase of the RF amplifier 28 a, which may be set to the desired phase (e.g., 0°) reference relative to the applied arbitrary RF signal input 104 in response to the phase control signal from the controller 24.

The phase compensator 108 provides a reference signal to an error correction amplifier 110 a (or error correction amplifier 110 b) at a positive input 112 a. The error correction amplifier 110 a is configured as an RF error correction amplifier that utilizes the reference signal at the positive input 112 a to control the output current, which is sensed by an RF current sensor 116 a and supplied to a negative input 114 a of the error correction amplifier 110 a. The error correction amplifier 110 a outputs an RF control signal as a function of the reference signal and the detected output current. The RF current sensor 116 a may be a current transformer, which may be a component of the current sensor 43. The RF current sensor 116 a monitors the developed RF output current by converting the RF current to a signal voltage, which is then returned to the negative input 114 a of the error correction amplifier 110 a. A second frequency compensation network 126 a provides frequency stability feedback compensation to the developed RF output current.

The first loop 100 a also includes a gain selector 118 a that provides a gain control adjustment to the output current control signal based on the gain controls signal supplied by the controller 24. The gain selector 118 a is connected to the negative input 114 a of the error correction amplifier 110 a and provides gain modification to the RF current sensor 116 a. The gain selector 118 a is coupled to a first frequency compensating network 120 a, which is used by the error correction amplifier 110 a to map the output current to the applied reference voltage from the phase compensator 108. The frequency compensating network 120 a provides stability corrected at the applied fundamental operating frequency of the arbitrary RF signal input to the sensed return signal detected by the RF current sensor 116 a.

The error-corrected output signal of the error correction amplifier 110 a is supplied to a gain amplifier 122 a, which is configured as an RF gain cell to provide a forward path gain for the error correction output signal. The output of the gain amplifier 122 a then drives the gate of the power component 102 a through a resistor element 124 a and RF coupler components 128 a as the drive signal is elevated to the operating voltage of the HVPS 27. RF coupler components 128 a may include, but are not limited to, a capacitor, a transformer, an optical coupler, combinations thereof, and the like. The gain amplifier 122 a also drives a second frequency compensating network 126 a to provide a second level of frequency compensation for the developed RF output current.

The power component 102 a is shown as a MOSFET device having a gate contact 134 a, a source contact 136 a and a drain contact 138 a. The power component 102 a presents a transconductance gain, converting the drive voltage from the gain amplifier 122 a to an RF output current, which is applied to the primary winding 38 a. The power component 102 a is coupled to a resistor element 130 a at the gate contact 134 a and a resistor element 132 a at the +V HVPS power. The resistor element 130 a establishes the DC bias operating level of the power component 102 a and the resistor element 132 a provides source degeneration to the developed current of the power component 102 a.

The RF amplifier 28 a also includes a stabilization amplifier 140, which is configured as a DC stabilization amplifier for monitoring the output DC voltage level generated by the output DC bias currents of the power components 102 a and 102 b flowing into a shunted resistor element 142. The DC voltage through the resistor element 142 is maintained at approximately 0 V DC by introducing steering error correction currents 144 a and 144 b via the stabilization amplifier 140 to the resistor elements 130 a and 130 b, respectively.

The stabilization amplifier 140 also provides a DC bias set point that establishes a relative transconductance gain match between power components 102 a (e.g., p-channel MOSFET) and power component 102 b (n-channel MOSFET), such that the positive and negative output peak currents delivered to the patient isolation transformer are symmetrically balances over the minimum and maximum dynamic range of the output current signal level.

Conventional electrosurgical generators have a slower response time in delivery of RF energy to the tissue, which results in less than optimal tissue effect. In particular, the response is slowed by the high voltage power supply, which controls the rate of change with which RF energy can be delivered to the tissue site. In such designs, a controller initially drives the high voltage power source, which then drives the RF output stage.

Further, conventional generators are based on various resonant output topologies. Resonant RF energy source operate at a unique switching frequency, which delivers both a fundamental RF operating frequency as well as additional switching frequency harmonics. The harmonic frequency components deliver an uncontrolled corruptive level of energy to the tissue, which may result in undesirable tissue effects. The harmonic frequency components also increase the RF high frequency leakage present in energy delivered to the patient.

Resonant-based RF generators also include reactive LC (inductor/capacitor) components to establish resonant operation. The LC components act as energy storage components due to resonant switching operation and may also discharge the stored energy into the tissue, thereby also resulting in undesirable tissue effects.

While several embodiments of the disclosure have been shown in the drawings and/or discussed herein, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto. 

What is claimed is:
 1. An electrosurgical generator comprising: a phase compensator configured to generate a reference signal based on a radio frequency signal and a phase control signal; at least one error correction amplifier coupled to the phase compensator, the at least one error correction amplifier configured to output a control signal based on the reference signal; a first radio frequency amplifier configured to generate a first component of at least one electrosurgical waveform based on the control signal and the phase control signal; a second radio frequency amplifier configured to generate a second component of the at least one electrosurgical waveform based on the control signal and the phase control signal; and a patient isolation transformer coupled to the first radio frequency amplifier and the second radio frequency amplifier, wherein the first and second components of the at least one electrosurgical waveform are combined at the patient isolation transformer to generate the at least one electrosurgical waveform.
 2. The electrosurgical generator according to claim 1, further comprising: a gain selector configured to provide a gain control adjustment to the control signal based on a gain control signal.
 3. The electrosurgical generator according to claim 2, further comprising: at least one gain amplifier coupled to the at least one error correction amplifier and the gain selector, the at least one gain amplifier configured to adjust the control signal based on the gain control adjustment.
 4. The electrosurgical generator according to claim 1, further comprising: at least one current sensor coupled to at least one of the first radio frequency amplifier or the second radio frequency amplifier, the at least one current sensor configured to provide a signal representative of the at least one electrosurgical waveform to the at least one error correction amplifier.
 5. The electrosurgical generator according to claim 4, further comprising: at least one frequency compensation network coupled to the at least one current sensor.
 6. The electrosurgical generator according to claim 1, further comprising: at least one stabilization amplifier coupled to at least one of the first radio frequency amplifier or the second radio frequency amplifier, the at least one stabilization amplifier configured to introduce an error correction current into the at least one electrosurgical waveform based on DC bias current flowing from the at least one of the first radio frequency amplifier or the second radio frequency amplifier.
 7. The electrosurgical generator according to claim 1, further comprising: a user input for selecting at least one electrosurgical operational mode; and a controller configured to adjust at least one of the radio frequency signal or the phase control signal in response to the at least one electrosurgical operational mode.
 8. An electrosurgical generator comprising: a phase compensator configured to generate a reference signal based on a radio frequency signal and a phase control signal; at least one error correction amplifier coupled to the phase compensator, the at least one error correction amplifier configured to output a first control signal and a second control signal based on the reference signal; a first radio frequency amplifier configured to generate a first component of at least one electrosurgical waveform based on the first control signal and the phase control signal; a second radio frequency amplifier configured to generate a second component of at least one electrosurgical waveform based on the second control signal and the phase control signal; and a patient isolation transformer coupled to the first radio frequency amplifier and the second radio frequency amplifier, wherein the first and second components of the at least one electrosurgical waveform are combined at the patient isolation transformer to generate the at least one electrosurgical waveform; a user input for selecting at least one electrosurgical operational mode; and a controller configured to adjust at least one of the radio frequency signal or the phase control signal in response to the at least one electrosurgical operational mode.
 9. The electrosurgical generator according to claim 8, further comprising: a first gain selector configured to provide a first gain control adjustment to the first control signal based on a first gain control signal provided by the controller; and a second gain selector configured to provide a second gain control adjustment to the second control signal based on a second gain control signal provided by the controller.
 10. The electrosurgical generator according to claim 9, wherein the at least one error correction amplifier includes a first error correction amplifier and a second error correction amplifier, wherein further comprising: the first error correction amplifier is coupled to the phase compensator and configured to output the first control signal based on the reference signal; and the second error correction amplifier is coupled to the phase compensator and configured to output the second control signal based on the reference signal.
 11. The electrosurgical generator according to claim 10, further comprising: a first gain amplifier coupled to the first error correction amplifier and the first gain selector, the first gain amplifier configured to adjust the first control signal based on the first gain control adjustment; and a second gain amplifier coupled to the second error correction amplifier and the second gain selector, the second gain amplifier configured to adjust the second control signal based on the second gain control adjustment.
 12. The electrosurgical generator according to claim 11, further comprising: a first current sensor coupled to the first radio frequency amplifier, the first current sensor configured to provide a signal representative of the first component of the at least one electrosurgical waveform to the first error correction amplifier; and a second current sensor coupled to the second radio frequency amplifier, the second current sensor configured to provide a signal representative of the second component of the at least one electrosurgical waveform to the second error correction amplifier.
 13. The electrosurgical generator according to claim 12, further comprising: a first frequency compensation network coupled to the first current sensor; and a second frequency compensation network coupled to the second current sensor. 